On 8/3/17 02:00, Phil Turmel wrote:
Hi Adam,
{Please remember to trim repetitive stuff, and interleave.}
On 03/07/2017 09:06 AM, Adam Goryachev wrote:
BTW, just some more info I've found... either almost the entire
drives are RAID1 mirrors, or all 4 are RAID1 mirrors:
OK, so I now have the following:
root@ubuntu:~# cmp /dev/sda /dev/sdb
/dev/sda /dev/sdb differ: byte 1000162959365, line 243319233
root@ubuntu:~# cmp /dev/sdc /dev/sdd
/dev/sdc /dev/sdd differ: byte 1000162971653, line 243236929
root@ubuntu:~# cmp /dev/sdb /dev/sdc
/dev/sdb /dev/sdc differ: byte 499637813249, line 54927275
So drives sda/sdb are almost complete mirror, and drives sdc/sdd are
almost complete mirror.
On top of that, the first half of all four drives are a complete mirror
(which seems oversized considering a "small" root RAID1 drive....)
Why there is a difference half way, and whether they are more difference
after that point I haven't yet checked, but that looks like something to
come back to...
Other option, they have been re-initialised/zero'd or similar, and
thats why all the data is identical (useless). I was hoping to get a
starting point for where the partition boundaries might have been
....
Search the devices for ext2/3/4 superblocks, like so:
dd if=/dev/sdX bs=1M 2>/dev/null |hexdump -C |grep '30 .\+ 53 ef 0'
What is the chance it is a ext2/3/4 based FS? I suppose most NAS would
use these filesystems... I guess I'll find out soon enough.
This will take a very long time, and will generate false positives.
Can you advise what to do to "verify" these and work out which ones are
false positives?
You probably would want to use screen or tmux to run these in
parallel in separate processes.
I'm not sure there is much of a point, since they are mostly duplicates
of each other. I'm running it on sdd now, and copying sda and sdc to a
spare drive. I may re-run the command on sdc (and skip the first
490GB...) if nothing useful is found on sdd.
But superblock locations will give you hints as to the rest of data,
and make it possible to create partitions that will let you copy
stuff off into a new array.
Sounds good, will see how it goes. Thanks for the advice!
Regards,
Adam
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